The invention relates to a continuously operating centrifuge drum for the sterilization of liquids, such as milk, fruit juices or the like, from which the extracted bacterial sludge is removed continuously or discontinuously. Such a centrifuge drum is known, for example, from German Pat. No. 1,062,185 (U.S. Pat. No. 3,217,982).
Centrifuges have been used for years for the sterilization of liquids, the sterilization of drinking milk and cheese making milk being of especial importance. According to known procedures, the milk that is to be sterilized is heated to the pasteurization temperature of about 72.degree. C, and is then centrifuged in high-speed centrifuges at high centrifugal force, for the purpose of completely removing the bacteria not killed by the pasteurization, especially the spore-forming bacteria.
German Pat. No. 1,062,185 cited above describes, for example, a method of sterilizing liquids in a disk centrifuge, in which the fluid in which the bacteria have been concentrated is removed from the area outside of the disk stack through a free liquid outlet. Since, however, the bacterial sludge is produced not only in liquid form but also in solid form, a portion of the bacterial sludge remains in the solids chamber of the drum and, as it accumulates in the drum the centrifuged milk becomes reinfected with the bacteria, and it is essential to prevent this from happening.
The build-up of bacterial sludge in the solids chamber of centrifuges occurs not only in the centrifuge drums having imperforated side walls as shown in the above-cited patent, but also in the generally known nozzle centrifuges which have since come into use. The same also applies to "nozzle desludgers," as they are called, i.e., combinations of nozzle centrifuges and self-cleaning centrifuges or of self-cleaning centrifuges only.
It is disadvantageous in these nozzle centrifuges that, depending on the number and spacing of the nozzles, cones of sludge are formed in the solids chamber which protrude into the separating chamber and continuously reinfect the outflowing, centrifuged liquid.